1. Field of the Invention
The invention relates to an implant, in particular an intervertebral prosthesis, consisting of an elongated elastic body.
2. Description of the Prior Art
A prosthesis of this type is known from EP-A-0 453 393. It serves as replacement for a damaged intervertebral disc nucleus (nucleus pulposus). With this prosthesis the outer ring (annulus fibrosus) of a natural intervertebral disc remains intact for the most part. The known prosthesis consists of a fluid-tight hollow body which is filled with an incompressible flowable medium. This prosthesis requires for its implantation a specially formed insertion instrument by means of which the hollow body is intraoperatively coiled up into a spiral form and can subsequently be filled. This places high demands on the skill of the surgeon on the one hand, as well as on the manufacture of the insertion instrument with respect to the coiling mechanism, as well as with regard to the filling apparatus. Furthermore, the leak-proofing criteria of the hollow body represent a long-term risk when the great stresses in the region of the vertebral column are taken into account. After the body has been rolled up in the intervertebral region and filled, the free end lies in contact with the annulus fibrosus, if the tool which acts at the center of the spiral for filling and sealing is removable without producing cavities. Only if no migration of spiral elements into other cavities can occur can the radially directed forces arising under the stress be compensated for and the spiral achieve the desired support function.